Spinning spindle



' Nov. 3, 1936.

E. H. HULL 2,059,872

SPINNING SPINDLE Filed Feb. 17, 1934 H ill [HI ooooooooooooooogggggpoooooo QOOOOOOOOOOOOOOOOOOOOOOOOOO:

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25 Invento'rz Edwin H. Hull, by 77 I Hi Atbo-r neg.

Patented Nov. 3, 1936 UNITED STATES PATENT OFFICE SPINNING SPINDLE EdwinH. Hull, Schenectady, N. Y., assignor to General Electric Company, acorporation of New York Application February 17, 1934, Serial No.711,766 22 Claims. (Cl.117-27.6)

is mounted on the motor shaft and driven thereby.

In motor-driven spinning spindles for spinning artificial silk whichrotate at a high speed, there are certain speeds called critical speeds,at which the spindle shaft is distorted from the axis of rotation, andwhile rotating in the distorted position causes severe vibrating forcesto be transmitted to the bearings in which the shaft rotates. The speedsat which the critical speeds occur depend upon the stiffness of thespindle shaft, the inertia of the stationary and rotating parts of thespindle, and the character of the mounting which is used to secure thespindle to the spinning frame.

The commercial spinning of artificial silk and the like has been done'atspeeds between 5,000 and 10,000 R. P. M. Only a small amount of spinninghas been done at 10,000 R. P. M. and the bulk of the spinning ofartificial silk is at speeds in the vicinity of 7,000 R. P. M. In allthe spinning spindles which have been successfully used for spinningartificial silk, the motor for driving the spindle has had a stationarymember of large and heavy construction with the spindle shaft, on whichthe spinning'bucket or other spinning device is mounted, supported inball bearings and purposely made flexible so that the normal operatingrange would be between the speeds at which critical vibration occurs.The operating range has usually been between the first and secondcritical speeds of the spindle shaft. With motors of this constructionand with the necessary high speeds of operation, it has not beenfeasible to make the shaft stiff enough so that the critical speed ofthe shaft 40 would be above the normal operating range. A

' spinning spindle having a motor with a flexible shaft is shown inapplication Serial'No. 701,478, filed Dec. 8, 1933, and assigned to thesame assignee as the present invention.

which will operate at high speeds and in which the operating rangeisbelow the speed at which the critical vibration of the spindle shaftoccurs.

An object of my invention is to provide a spinning spindle having anelectric motor with a,

stator of low inertia and a spinning bucket 55 In accordance with myinvention, I propose mounted on the motor shaft in which thefirstcritical speed of the motor shaft is above the normal operatingrange.

Another object of my invention is to provide a spinning spindle havingan electric motor with a stator of low inertia, a spinning bucketmounted on the motor shaft, and sleeve bearings of synthetic resin.

Another object of my invention is to provide a spinning spindle havingan electric motor with a stator of low inertia, a spinning bucket mount-.ed on the motor shaft, and sleeve bearings lubricated by water or awater solution.

Further objects and advantages of my invention will become apparent asthe following description proceeds, and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to andforming a part of this specification.

For a better understanding of my invention, reference may be had to theaccompanying drawing in.which the'single figure is a sectional view of aspinning spindle embodying my invention.

In the embodiment of my invention illustrated, the spinning spindle isdriven by an electric motor having a stationary member I, comprising astator frame 2 and endframes 5 and 6. In order to make the stationarymember light and of low inertia, the stator frame 2 is made fromaluminum and is cast directly around. a laminated field structure 3,having suitable windings 4, thereby holding the laminated fieldstructure in place. A flange I is cast integral with the stator 2 andextends horizontally from the stator to provide a mounting for themotor. The end frames 5 and 6 are also made of cast aluminumconstruction in order to decrease the weight, and each of these endframes has a suitable bearing secured therein. The upper end frame 5 hasa sleeve bearing 8 of fabric impregnated with a suitable synthetic resinsuch as a phenolic condensation product. The end frame 5 has an integralflange extending horizontally to form a mounting for the spindle. The.lower end frame 6 has a combined sleeve and thrust bearing 9 also madeof fabric impregnated with a r synthetic resin. The use of sleevebearings al lows the stator to be of light construction with lowinertia. The sleeve bearings also allow larger clearances between-theshaft and bearing than is possible with roller or ball bearings, andprovide a simple and rugged construction.

The rotating member of the electric motor comprisesa laminated corestructure l0 having a cast squirrel-cage winding I I therein and securedto a vertical shaft H. The shaft rotates inthe bearings 8 and 9 and hasa portion extending above the stationary member of the motor on which a,spinning bucket l3 or other suitable spinning device may be mounted. Thespinning bucket I3 is preferably frictionally driven by a clutch 28having an inner tapered portion 29 frictionally engaging the tapered endof the shaft I2 and having an outer tapered portion 30 which engages acomplementary portion 3| in the base of the bucket. The spinning bucketi3 is made of fabric impregnated with a phenolic condensation product.The inside diameter and inside depth are '7 inches and 4 inchesrespectively, and the total weight of the bucket is 4 pounds.

The bearing 8 and 9 are lubricated by water or a water solution which isbrought to the bearings by an external circulating system. The water isled from the external circulating system to the bearing 8 by pipe l4 andflows through horizontal passages l5 and I6 to the inner bearingsurface, through a vertical groove IT in the inner surface of thebearing to a chamber l8 at the top of the bearing, through grooves l9spaced around the outside of the bearing, over a baffle 20 extendingfrom a point adjacent the shaft l2 to the stationary member of themotor, and through a passage 2| in the stator frame 2 and the end frame6 to the sleeve and thrust bearing 9. The water lubricant flows into thebearing 9 through a passage 22, through a vertical groove 23 in theinner surface of the bearing to an outlet passage 24 at the top of thebearing, and out of the motor through a pipe 25 which is secured in anopening in the lower end frame 6 by a suitable coupling 25a. A sleeve2'! fitted in the end frame 6 and extending over the bearing 9 andaround the shaft l2 prevents the flow of water upwardly along the shaftinto the interior of the motor.

Due to the low viscosity of water, the bearing losses are low. The wateralso keeps the bearing cool and cools the motor during its passage overthe baffle 20 and through the passage 2|. A collar 26 is provided on theshaft l2 over the baffle 20 and prevents water from leaking into thewindings of the motor. It is possible to mix a corrosion preventer withthe water in order to prevent corrosion of ,the shaft and laminations,but I prefer to prevent corrosion by making the shaft l2 ofnon-corrosive steel and by placing a protective coating on thelaminations. Equivalent water solutions may be used in place of waterfor lubricating the bearings; for example, a solution of 80% water and20% glycerine is satisfactory. Water cooling of the motor allows thestator to be made lighter and with lower inertia.

The spinning spindle is secured to the spinning frame 32 by a compositemember forming a resilient mounting which comprises an inner ring 33 ofrubber or other material having low internal friction and a concentricouter ring 34 of cork or other material having high internal frictionextending along each of the upper and lower surfaces of the. spinningframe 32 coaxial with the spindle shaft. The lower rings extend betweenthe lower surfaceof the spinning frame 32 and the flange I on the statorframe 2. The upper rings extend between the upper surface of thespinning frame 32 and the flange 35 on the end frame. 5. The mountingmay be constructed with the inner ring of cork and the outer ring ofrubber. The motor is held in place by a clamping pressure exerted bybolts 36 between the stator frame 2 and the end frame 5. The resilientmounting is located so that the horizontal axis of the mounting coincideapproximately with the center of oscillation of the spinning spindlethroughout the normal running range. This axis is located between thetwo sets of shaft bearings and, in the embodiment illustrated in thedrawing, is somewhat nearer the upper bearing.

It is important that the electric motor have a stator of low inertia inorder that it may be feasible to make the shaft [2 of sufficientstiffness so that the operating range of the spinning spindle is belowthe speed at which critical vibration of the shaft takes place. With astiff shaft, there is less chance for distortion of the shaft duringabnormal operating conditions than in the case of the present flexibleshaft motor. the particular embodiment of my invention illustrated, themoment of inertia of the stationary member of the motor about an axisthrough the center of gravity of the stationary member of the motor andperpendicular to the axis of the shaft is equal to 0.085 lb. in secfl. Ifind that a satisfactory motor may be constructed if the inertia of thestator is less than 0.3 lb. in. sec). The stiffness of the shaft I2 iscalculated by considering the shaft as rigidly supported on knife edgesat the center of the bearings 8 and 9 with a theoretically rigidextension on the shaft and by applying a force to the rigid extension atthe center of gravity of the bucket. The ratio of the load applied tothe deflection at the point of application of the load is a measure ofthe stiffness of the shaft and in the case of the shaft illustrated, isequal to 9,200 1bs./in. I find that it is important that the ratio ofthe shaft stiffness to the moment of inertia. of the stator orstationary member of the motor be high, and in the case of the motorillustrated this ratio is equal to 272 in. It is also important that theratio of the shaft stiffness to the moment of inertia of the stator andspinning bucket about an axis through the center of gravity of thespindie and perpendicular to the axis of the shaft be high. In the caseof the spinning spindle illustrated, this latter ratio is equal to 40inf. I find that the spinning spindle will operate satisfactorily if theratio of shaft stiffness to the inertia of the stator of the motor isgreater than '70 inf-"3 or if the ratio of the shaft stiffness to themoment of inertia of the stator of the motor and the spinning bucketabout the center of gravity of the spindle is greater than 20 for. Bycomparison, the stator of the present flexible shaft motor for drivingspinning buckets has a moment of inertia of approximately 9 lb. in.see]; the ratio of shaft stiffness to stator inertia is approximatelyequal to 1.1 inrand the ratio of the shaft stiffness to the inertia ofthe bucket and stator about the center of gravity of the spindle isapproximately equal to .25 in.-. The ratios of shaft stiffness to momentof inertia are designated in terms of in.- because, in practice,engineers find it more convenient to determine moments of inertia (Jw)in terms of weight (w) of a body, for which the equation is:

Similarly, the expression for shaft stiffness (8) may be expressed as:

where, F=force applied in pounds, d=deflection in inches.

Then, the equation for the ratio of shaft stiffness to moment of inertiais:

E I, 2W1" Substituting, dimensional quantities gives:

i S in.

In the operation of the spinning spindle illustrated, at about 2,500 R.P. M. there are vibrations of the spinning spindle as a whole on themounting. These vibrations may be called the critical vibration of themounting. At this speed there is practically no distortion of thespindle shaft. There is no further vibration of the spinning spindleexcept that due to unbalance of the bucket until a speed substantiallyabove 12,000 R. P. M. is reached. At this higher speed, which is above15,000 R. P. M., the shaft I2 is subject to critical vibration. Thespinning spindle therefore has a very wide operating range extendingfrom about 4,000 R. P. M. up to 12,000 R. P. M. in which there is littlevibration. This range is ample for the present practice in spinningartificial silk. If the ratios referred to above are made larger,preferablyv by decreasing the stator inertia, the upper limit of thespeed of operation is increased. The lower limit of the speed ofoperation, which is dependent upon the mounting, remains substantiallythe same.

If the spinning spindle'has small unbalance, which is not the usual caseduring normal operation, there is a tendency for the shaft to whip inthe bearings; i. e., for the axis of rotation of the shaft to revolveabout the center of the bearings. This tendency to whip has beencorrected in the embodiment of my invention illustrated by the resilientmounting used to secure the spindle to the spinning frame. At highfrequencies of vibration, the cushioning effect of the mounting isobtained almost entirely from the inner rubber ring 33. At lowerfrequencies of vibration, such as caused by whipping of the shaft, thevibrating forces act upon the outer ring 34 which is of cork or othermaterial having high internal friction. The internal friction in thecork is sufficient to damp out these low frequency vibrations andeffectively prevent whipping of the shaft.

Although I have shown a particular embodiment of my invention, I do notdesire to be limited to the construction described, and I intend in theappended claims to cover all modifications which do not depart from thespirit'and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

l. A spinning spindle comprising an electric motor including astationary member and a rotatable member having a vertical shaftextending from said motor, a water-lubricated sleeve bearing ofsynthetic resin between said shaft and said stationary member and abovesaid rotating member, a baffle below said bearing and extending oversaid rotating member, means conducting water over said bailie forcooling said motor, and a spinning device adapted to rotate at speedsgreater than 4000 R. P. M. mounted on the extended portion of said'shaftand driven thereby.

2. A spinning spindle comprising an electric motor including astationary member of small mass and a rotatable member having a verticalstiff shaft with the first critical speed thereof above the normaloperating range of said spindle, said shaft having such stiffness andsaid stationary member such low moment of inertia that the ratio ofshaft stiffness to the moment of inertia of said stationary member aboutan axis through the center of gravity thereof and perpendicular to theaxis of said shaft is greater'than 70 in. a spinning device adapted torotate at speeds greater than 4000 R. P. M. mounted on and driven bysaid shaft, means including a sleeve bearing of synthetic resin forsupporting said rotatable member within said stationary member, andmeans having its critical vibration below the normal operating range ofsaid spindle for resiliently securing the same to a spinning frame orthe like.

3. A spinning spindle comprising an electric motor including astationary member having a horizontally extending flange and a rotatablemember including a vertical shaft, a spinning device mounted on anddriven by said shaft, and means having the critical vibration thereofbelow the normal operating range of said spindle and mass and arotatable member having a vertical stiff shaft with the first criticalspeed thereof above the normal operating range of said spindle,

a spinning device adapted to rotate vat speeds greater than 4000 R. P.M. mounted on and driven by said shaft, means including awaterlubricated sleeve bearing of synthetic resin for supporting saidrotatable member within said stationary member and for providing a smallradius of gyration to said stationary member, means including waterlubricant for cooling said motor, and means having the criticalvibration thereof below the normal operating range of said spindle forresiliently securing said spindle to a spinning frame or the like.

5. A spinning spindle comprising an' electric motor including astationary member of small mass and a rotatable member having a verticalstiff shaft, said shaft having such stiffness and said stationary memberhaving such low moment of inertia that the ratio of shaft stiffness tothe moment of inertia of said stationary member .about an axis throughthe center of gravity thereof and perpendicular to the axis of saidshaft is greater than '70 in. and a spinning device mounted on anddriven by said shaft.

6. A spinning spindle comprising an electric motor including astationary member of small mass and a rotatable member having a verticalstiff shaft, said shaft having such stiffness and said stationary memberhaving such low moment of inertia that the ratio of shaft stiffnesstothe said stationary member having such low moment of inertia that theratio of shaft stiffness to the moment of inertia of said stationarymember about an axis through the center of gravity thereof andperpendicular to the axis of said shaft is greater than 70 in. meansincluding a sleeve bearing of fabric impregnated with synthetic resinfor supporting said shaft within said stationary member, and a spinningdevice mounted on and driven by said shaft.

8. A spinning spindle comprising an electric motor including astationary member of small mass and a rotatable member having a verticalstiff shaft, said shaft having such stiffness and said stationary memberhaving such low moment of inertia that the ratio of shaft stiffness tothe moment of inertia of said stationary member about an axis throughthe center of gravity thereof and perpendicular to the axis of saidshaft is greater than 70 insmeans including a water lubricatedsleevebearing of synthetic resin for supporting said shaft within saidstationary member, means including water lubricant for cooling saidmotor and for lubricating said bearing, and a spinning device mounted onand driven by said shaft.

9. A spinning spindle comprising an electric motor including astationary member and a rotatable member having a vertical shaft, saidshaft having such stiffness that the ratio of shaft stiffness to themoment of inertia of said stationary member about an axis through thecenter of gravity thereof and perpendicular to the axis of said shaft isgreater than '70 in.- means including a water lubricated sleeve bearingof synthetic resin for supporting said shaft within said stationarymember, means for supplying water lubricant to said bearing, meansincluding a baffle below said bearing for conducting the water lubricantover said stationary member to cool the same, and a spinning devicemounted on and driven by said shaft.

10. A spinning spindle comprising an electric motor includingastationary member having a horizontal flange and a rotatable memberhaving a vertical shaft, said shaft having such stiffness that the ratioof shaft stiffness to the moment of inertia of said stationary memberabout an axis through the center of gravity thereof and per pendicularto the axis of said shaft is more than 70 in, a spinning device mountedon and driven by said shaft, and means including a ring ofresilientmaterial of high internal friction and a ring of resilientmaterial of low internal friction arranged between said flange and aspinning frame or the like for providing a mounting for said spindle.

11. A spinning spindle comprising an electric motor including astationary member of small mass and a rotatable member, a spinningdevice, and means including a stiff shaft for driving said spinningdevice, said shaft having such stiffness and said stationary memberhaving such low moment of inertia that the ratio of shaft stiffness tothe moment of inertia of said spinning device and said stationary memberabout an axis through the center of gravity of said spindle andperpendicular to the axis of said shaft is more than 20 inf 12. Aspinning spindle comprising an electric motor including a stationarymember having a horizontal flange and a rotatable member having avertical shaft, a spinning device mounted on said shaft and driventhereby, and means having the critical vibration thereof below thenormal operating range of said spindle and including a ring of resilientmaterial of low internal friction and an adjacent ring of resilientmaterial of high internal friction arranged between said flange and aspinning frame or the like for providing a mounting for said spindle.

13. A spinning spindle comprising an electric motor including astationary member having a horizontal flange and a rotatable memberhaving a vertical shaft, a spinning device mounted on said shaft anddriven thereby, and means having the critical vibration thereof belowthe normal operating range of said spindle and including a ring ofresilient material of low internal friction and a ring of resilientmaterial of high internal friction arranged coaxially with said shaftbetween said flange and a spinning frame or the like for providing amounting for said spindle.

14. A spinning spindle comprising an electric motor including astationary member having a horizontal flange and a rotatable memberincluding a vertical shaft, said shaft having the first critical speedthereof above the normal op erating range of said spindle, a spinningdevice mounted upon and driven by said shaft, and means having thecritical vibration thereof below the normal.operating range of saidspindle and including a ring of resilient material of low internalfriction and an adjacent ring of resilient material of high internalfriction arranged coaxially with said shaft between said flange and aspinning frame or the like for providing a resilient mounting for saidspindle.

15. A spinning spindle comprising an electric motor including astationary member having a horizontal flange and a rotatable memberhaving a vertical shaft, a spinning device mounted on said shaft anddriven thereby, and means having the critical vibration thereof belowthe normal operating range of said spindle and including a member havinga composite arrangement of resilient material of low internal frictionand a resilient material of high internal friction arranged between saidflange and a spinning frame or the like for providing a mounting forsaid spindle.

16. A spinning spindle comprising an electric motor including astationary member having a horizontal flange and a rotatable memberhaving vertical shaft, said shaft having the first critical speedthereof above the normal operating range of said spindle, a spinningdevice mounted on and driven by said shaft, and means having thecritical vibration thereof below the normal operating range of saidspindle and including a ring of resilient material arranged between saidflange and a spinning frame or the like with the horizontal axis of saidmeans in substantial coincidence with the normal center of oscillationof said spindle for providing a mounting for said spindle.

17. A spinning spindle comprising an electric motor including astationary member having a horizontal flange and a rotatable memberhaving vertical shaft, said shaft having the first critical speedthereof above the normal operating range of said spindle, a spinningdevice mounted on and driven by said shaft, and means having thecritical vibration thereof below the normal operating range of saidspindle and including a ring having a composite arrangement of resilientmaterial of low internal friction and a resilient material of highinternal friction arranged between said flange and a spinning frame orthe like for providing a mounting for said spindle, the horizontal axisof said last mentioned means being in substantial coincidence with thenormal center of oscillation of said spindle.

18. A spinning spindle comprising an electric motor including astationary member of small mass and a rotatable member including avertical stiff shaft, said shaft having the first critical speed thereofabove the normal operating range of said spindle, a spinning devicemounted on and driven by said shaft, means including water lubricatedsleeve bearings of synthetic resin adjacent each extremity of saidrotatable memher for supporting said rotatable member within saidstationary member and for providing a relatively small radius ofgyration to said stationary member, and mounting means having thecritical vibration thereof below the normal operating range of thespindle and having the horizontal axis thereof in a plane locatedbetween said sleeve bearings for resiliently securing said spindle to aspinning frame or the like.

19. A spinning spindle comprising an electric motor including astationary member and a rotatable member including a vertical shaft,said shaft having the first critical speed thereof above the normaloperating range of said spindle, a spinning device mounted on and drivenby said shaft, means including water lubricated sleeve bearings ofsynthetic resin adjacent each extremity of said rotatable member forsupporting said rotatable member within said stationary member, andmeans between said sleeve bearings and including a composite ring ofresilient material of high internal friction and resilient material oflow internal friction for providing a mounting for said spindle.

20. A spinning spindle comprising an electric motor including arotatable member having vertical stiff shaft and a stationary member ofsmall mass having a moment of inertia about an axis through the centerof gravity thereof and perpendicular to the axis of said shaft of lessthan 0.3 lb. in. sec. said shaft having such stiffness that the ratio ofshaft stiffness to the moment of inertia of said stationary member aboutan the ratio of shaft stiffness to the moment of inertia of saidspinning device and said stationary member about an axis through thecenter of gravity of said spindle and perpendicular to the axis of saidshaft is more than 20 in.

22. A spinning spindle comprising an electric motor including astationary member and a rotatable member having a vertical shaftextending from said motor and adapted to operate above 4000 R. P. M.,means including a sleeve bearing for supporting said shaft, saidextended portion of said shaft being adapted to rotate a spinning devicedriven thereby, and means for supplying water to the surfaces of saidstationary member of said motor and to the surfaces of said bearing tocool said stationary member and to cool and lubricate said bearing.

EDWIN H. HULL.

